1. Field
Embodiments disclosed herein generally relate to methods of forming inert carbon films. More specifically, embodiments generally relate to deposition of nanocrystalline diamond films using a remote plasma source.
2. Description of the Related Art
As the semiconductor industry introduces new generations of integrated circuits (IC's) having higher performance and greater functionality, the density of the elements that form those IC's is increased, while the dimensions, size and spacing between the individual components or elements are reduced. While in the past such reductions were limited only by the ability to define the structures using photolithography, device geometries having dimensions measured in um or nm have created new limiting factors, such as the conductivity of the metallic elements, the dielectric constant of the insulating material(s) used between the elements or challenges in 3D NAND or DRAM processes. These limitations may be benefitted by more durable and higher hardness hardmasks.
Diamond is known as a high hardness material. Due to high hardness, surface inertness, and low friction coefficient, synthetic diamond has been applied as a protective coating and in microelectromechanical systems (MEMS) among other uses. Diamond films, such as nanocrystalline diamond (NCD), have been synthesized by hot filament CVD and microwave CVD. However, there are a variety of difficulties with hot filament CVD and microwave CVD of nanocrystalline diamond films.
In hot filament CVD, a metal filament is used to activate the precursor gases for deposition. As expected, the metal filament is exposed to the precursor gases during the film forming process. As a result, precursor gases can react with the metal filament leading to metal contamination issues in the final product. Compared to hot filament CVD, microwave CVD has fewer contaminant issues. However microwave CVD requires a high process pressure which can affect the film uniformity. Moreover, although microwave plasma from microwave CVD has relatively low energy ions, these ions still can attack the NCD grain boundary and induce grain structure disorder.
Therefore, there is a need for improved methods for diamond film deposition.